A wireless LAN system is provided to make a frequency band setup task easy such that interference among base stations is reduced. The base station connected to a wired LAN includes a wired connection unit connected to the wired LAN and a wireless communication unit communicating with a LAN terminal via radio waves. The base station finds frequency bands already used by other devices in a place where the base station is installed and sets up a frequency band not used by the other devices as a frequency band to be used by the wireless communication unit to automatically set up a frequency band of radio waves to be used by the wireless communication unit.